Oversized-output error message now warns about byte-limited saved files

When a tool's output is too large to show directly and Claude Code saves it to a file instead, that saved file can itself be cut off at a byte limit. Now, when this happens, the error message shown to Claude explicitly notes that the saved file only contains the first N bytes or characters of the original output, that it may end in the middle of a structure, and that trying to parse it as JSON can therefore fail.